ST506 disk interface - Revision history

Jnc: +New cat

2023-12-02T15:20:42Z

+New cat

Jnc: Emphasize that it carries an analog signal, not a digital one;re-order a bit for better flow

2023-09-01T18:58:10Z

Emphasize that it carries an analog signal, not a digital one;re-order a bit for better flow

Jnc: /* External links */ add some useful pages

2023-09-01T13:41:21Z

‎External links: add some useful pages

Vaxorcist: Fixed "256-byte sector" to "512-byte sector"

2023-09-01T11:21:51Z

Fixed "256-byte sector" to "512-byte sector"

Vaxorcist: New page "ST506 disk interface"

2023-09-01T07:46:21Z

New page "ST506 disk interface"

New page

The '''ST506''' disk interface (other common names: ST-506, ST412, ST-412, or sometimes even the misleading MFM) was introduced in 1980 with the Seagate 5MB disk of the same name. The way to success was paved by the follow-up 10MB ST-412 disk model that was used by IBM for the IBM Personal Computer XT Model 5160. Soon many other hard disk manufacturers followed suit with their own models and thus helped the ST512 interface to be successful.

The ST506 interface has two two ribbon signal cables, one 34-pin control cable and one 20-pin data cable.

The control cable is shared by up to four disks whereas each disk has got its own dedicated data cable.
A lot of PC ST506 controllers support only two disk drives.

The data cables transmit the read and write signals, the control cable carries the control data such as:
* Ready
* Track 0
* Direction
* Step
* Index
* Seek Complete
* Head Select
* Drive Select
* Write Gate

The ST506 data rate is 5 Mbits/sec, and the code to store data on the magnetic media is [[MFM]].

The largest ST506 hard drive believed to have ever been made is the MAXTOR 2190, which gains about 159 MB from 1224 cylinders, 15 heads, and 17 256-byte sectors per track.

Later [[RLL]] technology increased storage capacity by 50% by squeezing 26 instead of 17 sectors into a track.

The largest ST506 hard drive believed to have ever been made is the MAXTOR 2190, which gains about 159 MB from 1224 cylinders, 15 heads, and 17 256-byte sectors per track.

Because of the identical hardware interface, RLL hard disks can be easily reformatted to MFM with suitable controllers. On the other hand, the opposite way is not recommended, since the higher sector density of RLL in MFM disks leads to serious problems with the reliability of data storage.

[[Category: Mass Storage]]

← Older revision		Revision as of 15:20, 2 December 2023
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	[[Category: Mass Storage]]		[[Category: Mass Storage]]
		+	[[Category: Interface Standards]]

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-The '''ST506 disk interface''' (other common names: ST-506, ST412, ST-412, or sometimes even the misleading MFM) was introduced in 1980 with the Seagate 5MB disk of the same name. The way to success was paved by the follow-up 10MB ST-412 disk model that was used by IBM for the IBM Personal Computer XT Model 5160. Soon many other hard disk manufacturers followed suit with their own models and thus helped the ST512 interface to be successful.
+The '''ST506 disk interface''' (other common names: '''ST412''', '''ST506/ST412''', or often the misleading '''MFM disk''') was introduced in 1980 by [[Seagate]] with the 5MB [[hard disk]] of the same name. It quickly became a ''de facto'' [[interface]] standard in the industry, although it was never formalized, or even given a formal name (hence the plethora of names for it used by people).
-The ST506 interface has two two ribbon signal cables, one 34-pin control cable and one 20-pin data cable.
+It provides the [[analog]] signal from the [[head]], not a [[digital]] bit stream (as later disk interface standards did). Most early [[device controller]]s used [[Modified Frequency Modulation|MFM]] [[encoding]] (hence the name, but that is misleading, for several reasons) on that to produce a bit stream, at a data rate of 5 Mbits/sec. Towards the end of its lifetime, [[run-length limited coding|RLL]] encoding was used instead.
-The control cable is shared by up to four disks whereas each disk has got its own dedicated data cable.
+(In addition to the replacement of MFM by RLL, 'MFM disk' is misleading as a name for this interface standard since MFM was widely used by other [[magnetic storage]] devices at the time; see [[Special:WhatLinksHere/Modified_Frequency_Modulation|here]] for some.)
-A lot of PC ST506 controllers support only two disk drives.
 The data cables transmit the read and write signals, the control cable carries the control data such as:
 * Ready
 * Track 0
@@ Line 16: / Line 24: @@
 * Drive Select
 * Write Gate
 ==External links==

@@ Line 1: / Line 1: @@
-The '''ST506''' disk interface (other common names: ST-506, ST412, ST-412, or sometimes even the misleading MFM) was introduced in 1980 with the Seagate 5MB disk of the same name. The way to success was paved by the follow-up 10MB ST-412 disk model that was used by IBM for the IBM Personal Computer XT Model 5160. Soon many other hard disk manufacturers followed suit with their own models and thus helped the ST512 interface to be successful.
+The '''ST506 disk interface''' (other common names: ST-506, ST412, ST-412, or sometimes even the misleading MFM) was introduced in 1980 with the Seagate 5MB disk of the same name. The way to success was paved by the follow-up 10MB ST-412 disk model that was used by IBM for the IBM Personal Computer XT Model 5160. Soon many other hard disk manufacturers followed suit with their own models and thus helped the ST512 interface to be successful.
 The ST506 interface has two two ribbon signal cables, one 34-pin control cable and one 20-pin data cable.
@@ Line 26: / Line 26: @@
 Because of the identical hardware interface, RLL hard disks can be easily reformatted to MFM with suitable controllers. On the other hand, the opposite way is not recommended, since the higher sector density of RLL in MFM disks leads to serious problems with the reliability of data storage.
 [[Category: Mass Storage]]

@@ Line 19: / Line 19: @@
 The ST506 data rate is 5 Mbits/sec, and the code to store data on the magnetic media is [[MFM]].
-The largest ST506 hard drive believed to have ever been made is the MAXTOR 2190, which gains about 159 MB from 1224 cylinders, 15 heads, and 17 256-byte sectors per track.
+The largest ST506 hard drive believed to have ever been made is the MAXTOR 2190, which gains about 159 MB from 1224 cylinders, 15 heads, and 17 512-byte sectors per track.
 Later [[RLL]] technology increased storage capacity by 50% by squeezing 26 instead of 17 sectors into a track.
-The largest ST506 hard drive believed to have ever been made is the MAXTOR 2190, which gains about 159 MB from 1224 cylinders, 15 heads, and 17 256-byte sectors per track.
+The largest ST506 hard drive believed to have ever been made is the MAXTOR 2190, which gains about 159 MB from 1224 cylinders, 15 heads, and 17 512-byte sectors per track.
 Because of the identical hardware interface, RLL hard disks can be easily reformatted to MFM with suitable controllers. On the other hand, the opposite way is not recommended, since the higher sector density of RLL in MFM disks leads to serious problems with the reliability of data storage.
 [[Category: Mass Storage]]